Allis FWD 8050 Powershift Issues
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=208890
Printed Date: 12 Jan 2026 at 5:28pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Allis FWD 8050 Powershift Issues
Posted By: devbow76
Subject: Allis FWD 8050 Powershift Issues
Date Posted: 11 Nov 2025 at 9:28pm
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Got a good one for you guys. Tractor quit moving so the powershift was pulled and hauled into the local dealer for a "rebuild". Got it back and installed it in the tractor. Worked for 5 hours then quit again. Dealer wouldn't warranty because they just got the powershift and not the whole tractor so we decided to split it. Found that there was multiple piston seals ripped. Replaced all the seals and reinstalled in the transmission. Its been working for over 50 hours now however its developed a random problem. It will be driving and happens in any range or powershift. It acts like someone shifted the transmission into neutral and it just coasts to a stop. The range and powershift were not moved nor the clutch pressed it will be driving just fine and then coast to a stop. If i mess with the range/powershift it will start going again. Sometimes its 5 minuets and sometimes its 45 minuets. Removed range transmission cover and when it acts up all the range gears stop turning but you can still hear the hum of the clutch drums turning so I'm convinced its in the powershift somewhere. Also when it acts up the steering, brakes, and pto all still work just wont move. All clutch pressures are perfect to spec when it acts up as well. Any ideas are greatly appreciated.
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Replies:
Posted By: DrAllis
Date Posted: 12 Nov 2025 at 7:23am
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Ripped or cut piston seals on one of those transmissions is the mark of someone who has never done one before. You have a hydraulic problem. Does the 1800 RPM light on the dash work????????? I assume not. Get it fixed so we can diagnose what is going on. Was the Power Shift valve disassembled and gone thru ???????? Again, I assume not.
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Posted By: devbow76
Date Posted: 12 Jan 2026 at 10:04am
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Sorry for the late reply I'm not very tech savvy. Checked pressure at all 1/8" pipe plugs for the a,b,c,d clutch's and when the tractor stops moving. Each clutch pressure does not drop. Stays good at 210psi which according to the manual is the correct pressure. Doesn't matter if the oil is cold or hot the result is still random. When the tractor stops moving with the range cover off of the top of the transmission. The gears stop turning but i can hear the hum of the powershift clutch packs still turning. It seems like there is a disconnect from the range transmission to the powershift. When i seen it split it looks like there was only a collar connecting the two but the splines were in great shape and there is no grinding noise at all when its driving or stopped. When i shift the powershift gears i can hear it shift in the powershift. rpm light on the dash works and does go out when required. Powershift valve was gone through and also replaced as the dealer had the parts cannon out .
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Posted By: DrAllis
Date Posted: 12 Jan 2026 at 11:12am
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Well, you've determined the PST seems to be working. The range transmission can't if it isn't turning. Has to be coupler related, but how can it re-couple itself ?? And how can the output shaft to the PST just quit turning and then decide to start again ?? Sounds like a split it (again) in the future. If that coupling isn't bad on the front of the range tranny, then it must be in the PST but I'd have no idea what. Somebody has to be first. You're him. EDIT: I don't have my service book in front of me. It only takes TWO of the six clutch packs to make the tractor move forward or reverse. I know the C2 clutch is for reverse. I know the C1 clutch is one of the two "inching" clutches. There is one more "inching" clutch, but I don't remember its name. Anyway, both inching clutches are applied in 3RD gear. To fully diagnose this, I guess you need at least 5 test gauges all hooked up at once. C2 is only for reverse, so you might be able to skip that one. This has to be a hydraulic problem, and proper diagnosis is crucial to a good outcome. Love to help. Wish you were closer. Someone has missed something in the valve itself or the hydraulic application of clutch packs.
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Posted By: 8070nc
Date Posted: 12 Jan 2026 at 3:25pm
This may be out of left field. Just thinking of anything that might help. It semms to me the inching valve is dumping pressure on the clutches causing the tractor to stop. Sinc you have had it apart i think id go through the procedure to adjust the inching valve to factory spec. That thing is sensitve and it doesnt take much to throw it off. You may have slready done that i dont know. Trying to think of anything to keep you from having to split it again
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1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
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Posted By: devbow76
Date Posted: 12 Jan 2026 at 3:58pm
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I will take any help at this point. My only question to that is i should see the clutch pressure in the a,b,c,d port drop shouldn't I?
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Posted By: devbow76
Date Posted: 12 Jan 2026 at 4:03pm
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Ok i also agree that it seems the powershift is working but i find it weird how the coupler could come undone and then slide back on. I was wondering what connects the input shaft from the engine to the range transmission. Does it go flywheel clutch pack then output shaft of powershift, then coupler, then range. Like what's the path of power maybe that'll help pinpoint this. I would like multigauge set like that but i only have a single gauge set as the multi is pricy.
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Posted By: devbow76
Date Posted: 12 Jan 2026 at 4:06pm
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I would also like to add the powershift pump has been flow and pressure tested passing with flying colors
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